Hydrocarbon conversion process with regeneration in two stages



FLUE GAS AIR M. F. NATHAN 2,852,443 HYDROCARBON CONVERSION PROCESS WITH REGENERATION IN TWO STAGES Filed May 22, 1953 FLUE GAS I R PRIMARY REACT-ON [GENERATOR PRODUCT J l I Am 66 ff 55 1 6) I 36 Y m 3s 4|57 HI 5 l l x 68 7 HT n I H i3,/|l l I ll STRIPPER I H REACTOR x STRIPPING GAS ll K I 1 l9 SECONDARY l REGENERATOR A 1 30 i W l5 87 1 9| I I I I I 89 ll RECYCLE on. FEED Ll FT GAS INVENTOR.

MARVIN F. NATHAN W ATTQR NEYS f United States Patent HYDROCARBON CONVERSION PROCESS'WITH REGENERATION IN TWO STAGES Marvin F. Nathan, New York, Nl Y., assignor to ,The .M. W. Kellogg Company, JerseyCity, N. J., a.corporation of Delaware Application May 22, 1953, Serial No. 356,799

14 Claims. Cl. 196-52 This invention relates to. an improved fluidizedoperation, and more particularly,,it. pertains to a method of supplying heat to an endothermic reaction zone in a fluid process, especially in. the case of a fluid reforming process.

.Many fluid hydrocarbon conversion processesrequire heat, because the reactions involved are, onthe whole, endothermic. Hydrocarbon conversion processes such as hydroforming, cracking, cracking under hydrogenpressure and the like require that substantial quantities of heat be supplied to effect the desired reactions." Various techniques have been employed for this purpose such as, for example, the use of a high cat'alystto oilfratio in catalytic cracking operations, .therecycling of thehydr-ogen containing gaseous product at a superaelevated temperature with respect to the conversion zone. in the case of the hydroforming process, etc. The use of. heated recycle gas for supplying heat in. the .hydroforming process involves recycling a given quantity of gaswhichlmay" or maylnot be optimum for the.hydroformingreactions.

. In such a case, the incentive isto .employless. recycle gas, and thus, reduce the cost of compression and heating for this purpose. On the other hand, thezuseof high catalyst to oil ratios for the purpose-of. supplying heat in a process such asv hydroforming does have an adverse eifect on product distribution, namely,. an-.undesired production of carbon and normallygaseous product materials. The above aspects of thehydroforming process have instigated workers to investigate the possibilities of supplying heat to an endothermic reaction zone with' little or no deviation from:optimum'productf-distribution and to attain this objective withlow operating and investment costs for commercial applications. .By means of the present invention a s cheme having..'substantial advantages With respect to the features mentioned above is proposed.

An object of this invention is toprovide-animproved hydrocarbon conversion process in -which-heatis-supplied by an eiiective and economical manner-to the-endothermi-c reaction zone.

Another object of thisinvention is to-provide arr-improved hydroforming process in which'theendothermic heat requirements of the reaction are supplied-without significant deviation from optimum product distribution.

Still another object of this invention-is to-provideau improved hydroforming process forlighthydrocarbon oils in which the endothermic heat requirement is.- supplied principally by heated catalyst-and-the-efifective catalystto oil ratio is maintained within: the range'desired for optimum performance.

- Other objects and advantages of this invention will become apparent from the following explanation'andflescription thereof.

In accordance with the present invention,:he'at can be supplied to an endothermic contactingizone' byfthe diiferential removal of combustibledeposits from a 'mass of finelydivided contact material in 'a manner-wherebyone vportion'is subjected under combustion conditionss'uitable p 1C6 Patented Sept. 16, 1958 for the elimination of a major quantity of the combustible deposits on the material and the other'portlon of .contact material is treated for the removal of a'minor amount of combustible deposits on the material. The portion of catalyst from which the smaller quantity of the total combustible deposits is removed serves principally to supply the heat required for the endothermic zone, and it is preferred that this portion'of contact material be circulated to'the contact zone in a COIldltion coming as closely as possible'to the combustible deposit content of the contact material present therein. Thus it' can be' seen that in the present invention, one portion of contact material or catalyst can be considered as being completely regenerated, in' the sense of being regenerated as nearly as possible to" the extent desired for the intended reaction in the endothermic contacting zone.-' On'the other hand, the remaining portion of contact material or catalyst is subjected to combustion conditions unde'r which the quantity of combustible de- 20posits'is burned in an amount sufficient to heat this portiori of material to a temperature required for supplying'heat to the endothermic contact zone. In this manner, the reaction or process in the endothermic zone is influenced primarily by the portion of material which is regenerated to a significantly greater extent than the remaining portion of catalyst which'is recycled to the endothermic zone in a state of so-called partial regeneration. Aspre'viously indicated, the combined streams of so-called completely regenerated and partially'regenerated catalyst or contact material are'subjected to a total regeneration treatment Which efiective1yremoves by combustion the amount of carbonaceous or combustible material whi'ch'is deposited on thefcontact material during'the endothermic contacting period, and which should be removed in order to maintain thedesiredprodrict distribution or result. I

The present invention is particularly"app l1cable 'for processes in which a catalyst to oil ratio in the order of"ab'out' 0.01 to about 1.0 or evenashighj'as 'about"2.0 orJmore is employed. This catalyst to 'oil'ratio is especi'allyefiective for thehydroforming reactions, because at' higher catalyst to oil ratios, there is a tendency for excessive quantities of carbon and normally gaseous products to be produced. At the catalyst to oil ratios just mentioned, the catalyst is recycled to the 'endo'thermiciconversion zone in a state which is regenerated to a substantially'great'er extent than the partially regenerated catalyst and contributes principally for effecting a given product distribution. 'For example, if the heat were to "be supplied to the conversion zone by'ineans other'th'an the presentinvention, the process would be operated with the catalyst to 'oil ratios designated above for the socalled completely regenerated catalyst. In thecase of a "catalytic cracking operation, a regenerated catalyst usually contains more than zero carbon content because,

forallpractical purposes, there is .littleor no commercial'value in attempting to regenerate the catalyst to a Ordinarily, for catalytic cracking to about 1.2% by weight of carbon. On' the other hand, a 'hyd'roforming process may ordinarily involve the re- .ge'nera'tionfof catalyst to an essentially 'zero content of carbon. This condition is very probable in view that .the type of catalyst which is employed promotes theoxidation of the carbonaceous material to the extent that the combustion -or regeneration reactions occur quite rapidly. I Usually, in the cement the hydroforming procschemesfcan be employed, via; (a) one in which-the catalyst to oil ratio is the same as used in conventional systems employing one regeneration zone, and the completely regenerated catalyst has a carbon content greater than is normally obtained by the single regeneration step; and (b) the catalyst to oil ratio is below that used conventionally, but the carbon content of the completely regenerated catalyst is maintained at the same level as is found in the conventional system. In both cases, the total production of carbon is the same as is produced in conventional systems, however, should the total carbon production increase by virtue of the practice of this invention, then it is also contemplated using a catalyst to oil ratio approximating a conventional system as Well as maintaining the carbon content of the completely regenerated catalyst at the same level as found in the conventional systems. In the method by which a lower catalyst to oil ratio is used than in conventional systems, the catalyst to oil ratio is reduced by an amount which will provide carbon for combustion in the secondary zone. In general, the catalyst to oil ratio can be reduced by an amount up to about 70% of the conventional catalyst to oil ratio, more usually, up to about 50% on the same basis. this invention the so-called completely regenerated catalyst in a catalytic cracking operation can have about 0.6 to about 2.5% by weight of carbon; whereas in a hydroforming process this so-called completely regenerated catalyst can have about 0.2 to 0.9% by weight of carbon. In general, the so-called completely regenerated solid material has about 55 to about 100% of its original combustible material content removed, although, in one aspect of the invention, about 65 to 95% of the original carbon content is removed. The other portion of catalyst being circulated and which serves principally as the heat carrying medium, is generally partially regenerated such that up to about 40% of its original carbon content is removed; however, on the Hence, under one aspect of average it is more desirable to remove less carbon from i the partially regenerated catalyst, in order that this portion of catalyst may behave essentially as the spent catalyst which is directly removed from the conversion zone for regeneration treatment. More usually, the partially regenerated catalyst can have about 10 to about of its original carbon content removed, and preferably, about 15 to about 25% of the original carbon content is removed in order to heat the catalyst to a temperature significantly above that exising in the conversion zone. For hydroforming, the spent catalyst of the present invention can contain about 0.1 to 5% by weight of carbon, more usually, about 0.5 to 2.5% by weight of the same; whereas for the general purposes of this invention for any process the combustible content can vary from about 0.05 to 15% by weight of the total material.

This invention is only applicable to a moving bed type of system in which catalyst is being circulated from one processing zone to another. Although the technique employed hereunder has particular applicability for fluidized operations, nevertheless, it can be used for the purpose of supplying heat to endothermic conversion zones in systems employing the catalyst in pellet or bead form of suflicient size to be used in a non-fluid condition in the processing vessels. Normally, for a fluidized operation, the catalyst has a size ranging from about 0 to about 250 microns, and more usually, about 10 to about 100 microns. The processing materials, whether it be the reactants in the reaction zone or the regeneration gas in the combustion or regeneration zone, are passed upwardly through a mass of finely divided contact material at a superficial linear gas velocity sufiicient toform a lean or dense phase of fluidized mass. For this purpose, the superficial linear gas velocities can range from about 0.1 to about feet per second, more usually,

about 0.1 to about 6 feet per second, and for commercial operations, it is preferred that this linear gas velocity be about 0.3 to about 2.5 feet per second.

intended reaction or process.

In the practice of this invention, the total mass of contact material being circulated is returned to the endothermic zone at a temperature of about 25 to about 400 F. greater than the temperature existing in the en dothermic zone. If the temperature difierence between the catalyst being returned to the endothermic zone and the temperature of the endothermic zone is small, it is then necessary, under some circumstances, to circulate relatively large quantities of catalyst for the purpose of supplying the heat required for the endothermic process. On the other hand, a large temperature difference between the catalyst being returned to the endothermic zone and the temperature of the endothermic zone makes possible the circulation of relatively smaller quantities of catalyst for the purpose of supplying heat. More usually, in this regard, the difierence between the temperature of the catalyst being circulated and the temperature in the conversion zone is about to about 200 F.

By means of this invention, it is possible to circulate any quantity of partially regenerated contact material or catalyst relative to the so-called completely regenerated contact material or catalyst as may be desirable for the type of process or reaction being considered. In this regard, the relative proportion of partially regenerated catalyst to so-called completely regenerated catalyst, on a weight basis, is about 0.5-15 to 1. However, while in practice the ratio or relative quantity of partially regenerated catalyst totso-called completely regenerated catalyst can be small, it is, nevertheless, of special significance to employ this invention in systems requiring the use of relatively greater quantities of regenerated catalyst to socalled completely regenerated catalyst for the purpose of supplying heat. Accordingly, this invention is used in systems requiring about 1 to about 5 parts by weight of partially regenerated catalyst to 1 part of so-called completely regenerated catalyst in order to supply the necessary heat of reaction. The temperature to which the partially regenerated catalyst is heated may be higher, lower or equal to the temperature of the so-called completely regenerated catalyst being recycled to the conversion zone. In general, the temperature to which the catalyst can be heated is governed by the thermal stability of the catalyst, and this temperature is usually in the order of about 1150 F. or, in

some cases about 1200 F. For many commercial operations in present use, the upper limit of temperature is about 1100 F. and this represents a substantial safety factor, because higher temperature can be tolerated without causing quick deactivation of the catalyst.

In the above description, it was noted that two portions of contact material are regenerated to different levels of combustible content, the portion being more completely regenerated is equivalent in quantity to what is ordinarily used in a conventional process to attain the It should be understood, however, that this method also includes an operation in which one portion of contact material, for example, a

reforming catalyst is regenerated to zero carbon content and the remainder is regenerated partially as discussed above. The difference is that the quantity of actual completely regenerated contact material is less than the amount which would be used, if it were desired to maintain the catalyst to oil ratio falling within the optimum quantity under conventional conditions.

As previously indicated, this invention is applicable to any hydrocarbon conversion process in which heat is required for the hydrocarbon reactions. In views that the hydroforming process is conducted preferably at relatively low catalyst to oil ratios, this invention is especially effective for supplying heat to this type of process. In a hydroforming process, the catalyst is one which has the properties of forming aromatics or it is called an aromatizing catalyst which is capable of dehydrogenatin'g naphthenes, isomerizing and cracking acyclic and cyclic hydrocarbons, and dehydrocyclizing acyclic hydrocarbons. Catalysts found useful for this purpose include the sulfides and/or oxides of the left hand elements of group VI, the oxides and/or sulfides of the group V metals, the noble metals of group VIII, etc. Specific examples of catalytic elements having the properties mentioned above are molybdenum trioxide, tungsten oxide, chromia, platinum, palladium, vanadium oxide, etc. These catalytic elements are used alone or they are supported on a suitable carrier material such as, for example, alumina, zinc spinel, silica, magnesia, titanla, zirconia, silica-alumina, bauxite, charcoal, alumina-thoria, etc. Another class of catalytic elements which are specially effective for the hydroforming reactron are the heteropoly acids such as, for example, phosphomolybdic acid, silicomolybdic acid, germanomolybdic acid, chromiomolybdic acid, etc. These catalytic elements may be used alone or they can be supported on the carrier materials mentioned above. In general, the catalytic element constitutes about 0.1 to about 50% by weight, more usually, about 0.5 to about 20% by weight, based on the total catalyst.

The feed stock to be reformed by means of the present invention is a light hydrocarbon oil and includes, for example, gasoline, naphtha and kerosene. The light hydrocarbon oil can have an initial boiling point of about 85 to about 325 F. and an end point of about 300 to about 500 F. In the case of reforming a naphtha fraction, it is preferred to employ a naphtha having an initial boiling point of about 100 to about 250 F. and an end point of about 350 to about 450 F. Generally, the light hydrocarbon oil to be reformed has a Watson characterization factor of about 11.50 to about 12.20. The feed material can be one which is a straight run or virgin stock, a cracked stock which is derived from a thermal or catalytic cracking operation, or amixture. or a blend of straight run and. cracked stocks. Accordingly, the octane number of the feed material can be at least 5 CFRR clear, or more usually, about 20 to about 70 CFRR clear and the olefin content of the oil can vary from about 0 to about 30 mol percent. This light hydrocarbon oil can be derived from any type of crude oil, consequently, it can contain sulfur in the amount of 0 to about 3.0 percent by weight.

The light hydrocarbon oil is reformed under conditions which can inolve net, consumption or net production of hydrogen. A system involving a net production of hydrogen is commonly referred to hereunder as bydroforming, and its is operated under such conditions that the quantity of hydrogen produced is sufiicient to sustain the process without the need for extraneous hydrogen. Generally, for the reforming of light hydrocarbon oils, a temperature of about 750 to about 1100 F., is employed. At this temperature, the pressure of the operation is generally maintained at about 25. to about 1000 p. s. i. g. The quantity of oil processed relative to the amount of catalyst employed is measured in terms of weight space velocity, that is, the pounds of oil feed on an hourly basis charged to the reaction zone per pound of catalyst which is present therein. The weight space velocity can vary from about 0.05 to about 10. The quantity of hydrogen which is added to the process is usually measured in terms of the standard cubic feet of hydrogen (measured at 60 F. and 760 mm.) per barrel of oil feed charged to the reforming operation (1 barrel=42 gallons). On this basis, the hydrogen rate is about 500 to about 20,000 S. C. F. B. Another method of indicating the quantity of hydrogen which can be present during the reforming operation is by means of hydrogen partial pressure. In this regard, the hydrogen partial pressure is about to about 950 p. s. i. a. in the reaction zone, based on inlet conditions.

Ina hydroforming operation, the reactionv conditions fall within the ranges specified hereinabove, however, they are selected on the basis of obtaining a net prodnet ofhydrogen. A preferred hydroforming process involves a temperature of about 850 to about 1050" F.; a pressure of about 50 to about 500 p. s. i. g.; a weight space velocity of about 0.1 to about 3; a hydrogen rate of about 1000 to about 7500 S. C. F. B. and a hydrogen partial pressure of at least about 25 p. s. i. a. and up to the point at which hydrogen is consumed.

The regeneration treatment for the removal of carbonaceous material from the contact material is conducted at a temperature of about 800 to about 1200" F. and preferably, at a temperature of about 950 to about 1150 F. This treatment is effected with an oxygen containing gas, e. g., oxygen, air, diluted air having about 1 to about 10% by volume of oxygen, etc. These conditions can be used for either partial or complete regeneration and, as previously mentioned, the temperature can be higher orlower for one treatment over the other, depending upon the result desired.

For a better understanding of the present invention, reference will be had to a specific example based on the accompanying drawing.

In the figure, the reactor 5 is a vertical, cylindrical vessel upon which there is superimposed a primary regenerator 7, which is'also a vertical, cylindrical, container. The reactor holds a fluidized bed of catalyst, e. g., 9% by weight of molybdenum trioxide on alumina, having a level 9. The catalyst is withdrawn from the reactor through a stripper well 11, which is formed by a vertical transverse bafile 13. The withdrawn catalyst passing through the stripper well 11 flows into a standpipe 15. Near the bottom of standpipe 15, there is situated a control valve 17 which serves to control automatically the flow of catalyst passing therethrough. In stripper well 11, a shipping gas is introduced into the bottom part thereof through a supply source 19 and-this stripping gas enters the stripper-well. through a distributor 21. The stripped catalyst is discharged from the standpipe 15 into a lift vessel 25. Lifting gas is admitted into lift vessel 25 at the bottom end thereof by means of a supply line 27. This lift vessel 25 is a cylindrical body whose upper end is of gradually reduced cross-sectional area, in turn is connected. toa cylindrical, vertical rise 30.

The vertical, cylindrical riser 30 extends upwardly through the reactor 5 and terminates inside the upper portion of primary regenerator 7. At the bottom end of reactor 5, recycle gas containing hydrogen is admitted through a line 32; whereas oil feed is admitted through a line 34. A cyclone separator 36 is situated in the upper part of the reactor for the purpose of separating entrained catalyst fines from the outgoing reaction prod uct, and returning the same to the catalyst bed by means of a dipleg 38. The oil. feed is admitted into'the bottom I part of the catalyst bed in reactor 5 through a conicalshaped distributor 40. The primary regenerator 7 serves to partially regenerate the catalytic material. and this' is accomplished by means of air which is admitted. into the bottom part thereof by means of a line 44. A fluidized bed of catalyst is maintained in the primary regenerator having a level 46. Entrained catalyst fines are removed substantially from the flue gas by means of cyclone 48, and they are returned to the catalyst bed by means. of a dipleg 50. The flue gas product substantially free of entrained catalyst is discharged through a. line 52. Partially regenerated catalyst is recirculated to the reactor by means of a standpipe 55. This standpipe. originates at the bottom part of the primary regenerator 7, and it terminates at the middle portion of the reactor. This partially regenerated catalyst standpipe contains a slide valve 57 which serves to regulate automatically the flow of catalyst therethrough. The reaction product leaving the reactor 5, substantially free of catalyst fines, is discharged through a line 61'.

A portion of the. partially regenerated catalyst flows into a well- 63 which is situated within the bottom part of the primary regenerator, and thence, it flows through a standpipe 66. This standpipe contains a slide valve 68 for the purpose of automatically controlling the flow of catalyst through it. The partially regenerated catalyst is fed from standpipe 66 into the secondary regenerator comprised of a lower cylindrical section 70 and an upper enlarged cylindrical section 72. In section 70 of the regenerator a catalyst bed is maintained having a level 74, and the temperature in this section is regulated by means of cooling coils 76. The upper enlarged section 72 serves as a disengaging zone for the main body of catalyst and any entrained material is removed to a substantial extent by means of a cyclone 78. The separated catalyst is returned to section 70 from the cyclone by means of dipleg 80. The flue gas substantially free of entrained catalyst is discharged from section 72 by means of a line 82. The air which is used for the purpose of completely regenerating the catalyst in section 70 is introduced at the bottom end thereof by means of a line 85. The completely regenerated catalyst is withdrawn from the bottom part of section 70, and it is passed through a standpipe 87 which is connected to the bottom part of reactor 5. This standpipe 87 contains a slide valve 89 for automatically controlling the rate of catalyst which passes through it. The completely regenerated catalyst is admitted into the reactor through a Well 91 which is connected to standpipe 87.

In operation, naphtha having an initial boiling point of 190 F. and an end point of 381 F. is fed to the reactor at the rate of 30,000 barrels per stream day or 352,000 pounds per hour. The naphtha vapors are at a temperature of 935 F. Recycle gas containing about 60% by volume of hydrogen is fed through line 32 at the rate of about 2500 S. C. F. B. This recycle gas is at a temperature of about 1200 F. The reaction pressure maintained in reactor 5 is 250 p. s. i. g. The quantity of naphtha which is fed to the reactor relative to the quantity of catalyst which is present therein provides a weight space velocity of about 0.30. Spent catalyst is withdrawn from the reactor through stripper well 11 at a rate sufficient to provide a catalyst to oil ratio of about 2.5. This catalyst is stripped with either steam or recycle gas. In the case of steam, the rate is about 25,000 pounds per hour, and the steam is at a temperature of about 500 F. The stripped catalyst flows from standpipe 15 into the lift vessel 25. In the lift vessel, steam is admitted through the bottom thereof by means of line 27 at a rate sufficient to provide a density of about pounds per cubic foot in vertical riser 30. The spent catalyst is discharged into the primary regenerator 7, which is maintained at a temperature of about 1100 F. The spent catalyst entering the primary regenerator contains about 1.3% by weight of carbon. Air is introduced into the bottom of the primary regenerator by means of line 44 at the rate of about 36,500 pounds per hours in order to burn about 20% by weight of the original carbon content of the spent catalyst. Partially regenerated catalyst having about 1% by weight of carbon is recycled to the reactor through standpipe 55, at a rate sufficient to provide a catalyst to oil ratio of 1.85. The remaining partially regenerated catalyst is discharged through well 63 into the primary regenerator, and it leaves through standpipe 66 at a rate sufficient to provide a catalyst to oil ratio of 0.65.

The partially regenerated catalyst is fed into section 70 of the secondary regenerator wherein it is contacted with air which is introduced at the rate of about 220,000 pounds per hour through line 85. The temperature of section 70 is maintained at 1100 F. by means of cooling coils 76. The total pressure in the secondary regenerator is maintained at 250 p. s. i. g. Partially regenerated catalyst is completely regenerated such that the catalyst leaving section 70 contains essentially zero percent carbon. Completely regenerated catalyst flows through standpipe 87 whereby it is admitted into the bottom part of reactor 5 through well 91.

Various kinds of apparatus can be used for the purpose of efiecting the present invention. In one alternative, the reactor can be the same as shown in the attached drawing, however, the primary regenerator is employed as a stripper in this alternative scheme. The catalyst is passed from the stripper to a regenerator which is comprised of two sections, the upper section being the primary regeneration zone and the lower section is the zone for accomplishing complete regeneration. A portion of the partially regenerated catalyst is passed by means of a standpipe from the upper partial regeneration zone to the lower complete regeneration zone. The remaining portion of partially regenerated catalyst is passed by means of a separate standpipe from the upper partial regeneration zone to the bottom part of the reactor. The completely regenerated catalyst is withdrawn from the lower complete regeneration zone by means of a separate standpipe which in turn may be connected to the standpipe containing the partially regenerated catalyst which flows to the bottom of the reactor. I11 this scheme, the complete regeneration zone is supplied with air, and it is cooled by means of tubes as shown in the attached drawing. The upper partial regeneration zone and the lower complete regeneration zone can be separated by means of a grid plate whereby flue gas containing oxygen passes from the lower complete regeneration zone to the upper partial regeneration zone. If necessary, auxiliary regeneration gas, air, can be supplied directly to the upper regeneration zone.

In another alternative scheme, the regeneration vessel is comprised of two zones. The upper zone is the com plete regenerator; whereas the lower zone is the partial regenerator. The completely regenerated catalyst is passed from the upper zone to the lower zone by means of a standpipe intercommunicating therebetween. The total spent catalyst stream is divided such that a portion is fed directly to the upper complete regeneration zone and the remaining portion is fed directly to the lower partial regeneration zone. Since the completely regen: erated catalyst is permitted to intermingle with the partially regenerated catalyst, the combined streams of completely and partially regenerated catalyst are passed to the reactor by means of a single standpipe leading from the lower partial regeneration zone to the reactor. Separate regeneration gas streams are fed to each of the regeneration zones under consideration.

Still another alternative scheme comprises a regeneration vessel which is comprised of a lower complete regeneration zone and an upper partial regeneration zone, the zones being connected by means of an elongated high velocity or lean phase zone. The total spent catalyst is divided so that a portion passes to the lower complete regeneration zone and the remaining portion is fed to the upper partial regeneration zone. The main air stream is fed to the lower complete regeneration zone along with cooled recycle flue gas which serves as a carrying medium as well as for cooling the complete regeneration zone. The entire flue gas stream containing excess oxygen serves to carry the completely regenerated catalyst as a lean phase through the connecting zone to the upper partial regeneration zone. If necessary, auxiliary air may be fed directly to the upper partial regeneration zone. The partially and completely regenerated catalysts are allowed to mix in the upper partial regeneration zone, and as a single combined stream, it is recirculated to the lower part of the reactor.

A still further alternative scheme involves a regeneration vessel which is comprised of a lower complete regeneration zone and an upper partial regeneration zone, which are separated by means of a grid plate. The total spent catalyst stream is divided so that a portion is fed directly to the upper partial regeneration zone and the remaining portion is fed directly to the lower complete regeneration zone. Separate regeneration gas streams, such as air, are fed in suitable quantities to each of. the regeneration zones, described above. If desired, the flue gas: from the lower complete regeneration zone is passedthroughthe upper partial regeneration zone in order to utilize any excess oxygen which might be. contained therein. The partially and completely regenerated catalyst, streams. are withdrawn separately from the regeneration zones by means of separate standpipes and, these in turn may be combined as a common standpipe, by means. of which the catalyst flows into the bottom part of the reactor.

Having thus provided a description of my invention. along with specific examples thereof, it should be understood that no undue. limitations or restrictions are to be imposed by reason thereof, but that the present invention isdefined by the appended claims.

Having described my invention, I claim:

1- A method of suppling heat to an endothermic contacting zone existing at an elevated temperature and containing a mass of finely divided contact material which contains combustible deposits comprising passing a portion of contact material containing combustible deposits. from the endothermic zone to a primary combustion zone wherein combustible deposits are removed by burning with an oxygen containing gas at a temperature above the temperature of the endothermic zone such that the resultant'contact material contains a major amount of the original combustible deposits, passing a portion of the contact material from the primary combustion zone to the endothermic contacting zone, passing another porof-the contact material from the primary combustion zone; to a, secondary combustion zone wherein combustible deposits are removed by burning with oxygen containing gasat. a temperature above the temperature in the endo thermic zone such that the resultant contact material contains a minor amount of the original combustible deposits, and passing the contact material from the secondary combustion zone to the endothermic zone, the total amount of contact material being circulated from the combustion zones being sufiicient to maintain the temperature of the endothermic zone.

2. A method of supplying heat to an endothermic zone existing at an elevated temperature and containing a mass of finely divided contact material contaminated with combustible deposits comprising passing a portion of; finely divided contact material from the endothermic zone to a primary combustion zone wherein not more than about, 40% of the combustible deposits contained in the. contact material is removed by burning with an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the endothermic. zone, passing a portion of the contact, material from the primary combustion zone to the endothermic zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means. of an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the contacting zone such that the contact material has about 55 to 100% of the original combustible material content removed, passing contact material from the secondary combustion zone to the endothermic zone, said contact material being circulated from the primary and secondary combustion zones to the endothermic zone having a weight ratio of the former to the latter of about 0.5l5:l and the total amount of regenerated material being sufiicient to maintain the temperature in the endothermic zone.

3. The process of claim 1 wherein the contact material comprises a molybdenum oxide catalyst.

4. The process of claim- 1 wherein the contact material comprises a heteropoly acid catalyst.

'5. The process of claim 1 wherein the contact material comprises a palladium catalyst.

6. A method of supplying heat to an, endothermic contacting zone existing at an elevated temperature. and containing a, mass of finely divided contact material which contains combustible deposits comprising passing a portion of contact material containing combustible deposits from theendothermic zone to a primary combustion zone wherein combustible deposits are removed by burning, with. an oxygen containing gas at a temperature above the temperature of the endothermic zone such that, the resultant contact material contains a major amount of the original combustible deposits, passing a portion of the contact material from the primary combustion zone. to. it secondary combustion zone wherein combustible deposits are removed by burning with an oxygen containing gas at a temperature above the temperature in the endothermic zone. such that the resultant contactmaterial con tains a minor amount of the original combustible deposits, and passing the contact material from the secondarycorrtbustion zone to the endothermic zone, the total amount of contact material being circulated from thecombustion zones beingsufiicient to maintain the temperature. of. the endothermic zone.

7. A method of supplying heat to .anendothermic, zone existing at an elevated temperature and containing a mass of fine y divided, contact material contaminated, with combustible. deposits comprising passing a portion of finely divided contact material from the endothermic zone to. a primary combustion zone wherein not more than about 40% of the combustible deposits contained in the contact material is removed by burning with an oxygen containing gas ata temperature of about 25. to about 400 greater than the temperature. in the endothermic zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means o n oXygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the. contacting zone such that the contactmaterial has about 55 .to about of the original combustible material content removed, passing contact'material from the. secondaryv combustion zone to the endothermic zone, the total amount of contact material being circu ated from the combustion zones being sufiicient to maintain the. temperature in the endothermic zone. 7

8. A method of supplying heat to an endothermic zone existing at an elevated temperature and containing amass of finely divided contact material contaminated with combustible deposits comprising passing a portion of finely divided contact material from the endothermic zone to a primary combustion zone wherein not more: than about 40% of the combustible deposits contained, in the contact material is removed by burning with an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the endothermic zone, passing a portion of contact material from the primary combustion zone to a, secondary combustion; zone wherein the combustible deposits. are burned by means of an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the contactingzone such that the contact material has about 55, to about 100% of the original combustible material content removed, passing contact material from-the secondary combustion zone to the endothermic zone, said contact material; being circulated from the primary and secondaty combustion zones to the endothermic zone having a weight ratiov of the. former to the latter of about 0.5 15 :1 and the, total amount of regenerated material being su ficient to maintain the temperature in the en.- dothermic zone. 7

9. Almethod of supplying heat to an endothermic zone existing at an elevated temperature and containing amass of finely divided contact material contaminated with combustible deposits comprising'passing a portion of finely divided contact material from the endothermic zone to a primary combustion zone wherein not more than about 40% of the combustible deposits contained in the contact material is removed by burning with an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the endothermic zone, passing a portion of the contact material from the primary combustion zone to the endothermic zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means of. an oxygen containing gas at a temperature of about 25 9 to about 400 greater than the temperature in the contacting zone such that the contact material has about 55 to about 100% of the original combustible material content removed, passing contact material from the secondary combustion zone to the endothermic zone, and the total amount of contact material being circulated from the combustion zones being suflicient to maintain the temperature in the endothermic zone.

10. A method of supplying heat to an endothermic zone existing at an elevated temperature and containing a mass of finely divided contact material contaminated with combustible deposits comprising passing a portion of finely divided contact material from the endothermic zone to a primary combustion zone wherein about 10 to about 35% of the combustible deposits contained in the contact material is removed by burning with an oxygen containing gas at a temperature of about to about 400 greater than the temperature in the endothermic zone, passing a portion of the contact material from the primary combustion zone to the endothermic zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means of an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the contacting zone such that the contact material has about 65 to about 95% of the original combustible material content removed, passing contact material from the secondary combustion zone to the endothermic zone, said contact material being circulated from the primary and secondary combustion zones to the endothermic zone having a weight ratio of the former to the latter of about 0.5-15 :1 and the total amount of regenerated material is sufiicient to maintain the temperature in the endothermic zone.

11. A method of supplying heat to a reforming zone existing at an elevated temperature and containing a mass of finely divided contact material which contains combustible deposits comprising passing a portion of contact material containing combustible deposits from the reforming zone to a primary combustion zone wherein combustible deposits are removed by burning with an oxygen containing gas at a temperature above the temperature of the reforming zone such that the resultant contact material contains a major amount of the original combustible deposits, passing a portion of the contact material from the primary combustion zone to the reforming zone, passing another portion of the contact material from the primary combustion zone to a secondary combustion zone wherein combustible deposits are removed by burning with an oxygen containing gas at a temperature above the temperature in the reforming zone such that the resultant contact material contains a minor amount of the original combustible deposits, and passing the contact material from the secondary combustion zone to the reforming zone, the total amount of contact material being circulated from the combustion zones being sufficient to maintain the temperature of the reforming zone.

12. A method of supplying heat to a reforming zone existing at an elevated temperature and containing a mass of finely divided contact material which contains combustible deposits comprising passing a portion of contact material containing combustible deposits from the reforming zone to a primary combustion zone whereincombustible deposits are removed by burning with an oxygen containing gas at a temperature above the temperature of the reforming zone such that the resultant contact material contains a major amount of the original combustible deposits, passing a portion of the contact. material from the primary combustion zone to a second-- ary combustion zone wherein combustible deposits areremoved by burning with an oxygen containing gas at a temperature above the temperature in the reforming zone such that the resultant contact material contains a minor amount of the original combustible deposits, and passing the contact material from the secondary combustion zone to the reforming zone, the total amount of contact material being circulated from the combustion zones being sufficient to maintain the temperature of the reforming zone.

13. A method for supplying heat to a reforming zone existing at an elevated temperature and containing a mass of finely divided contact material contaminated with oombustible deposits comprising passing a portion of finely divided contact material from the reforming zone to a primary combustion zone wherein .not more than about 40% of the combustible deposits contained in the contact material is removed by burning with an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the reforming zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means of an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the reforming zone such that the contact material has about 55 to about 100% of the original combustible material content removed, passing contact material from the secondary combustion zone to the reforming zone, the total amount of contact material being circulated from the combustion zones being suificient to maintain the temperature in the reforming zone.

14. A method of supplying heat to a reforming zone existing at an elevated temperature and containing a mass of finely divided contact material contaminated with combustible deposits comprising passing a portion of finely divided contact material from the reforming zone to a primary combustion zone wherein about 10 to about 35% of the combustible deposits contained in the con tact material is removed by burning with an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the reforming zone, passing a portion of the contact material from the primary combustion Zone to the reforming zone, passing another portion of contact material from the primary combustion zone to a secondary combustion zone wherein the combustible deposits are burned by means of an oxygen containing gas at a temperature of about 25 to about 400 greater than the temperature in the reforming zone such that the contact material has about 65 to about of the original combustible material content removed, passing contact material from the secondary combustion zone to the reforming zone, said contact material being circulated from the primary and secondary combustion zones to the reforming zone having a weight ratio of the former to the latter of about 05-15 :1 and the total amount of regenerated material is sufiicient to maintain the temperature in the reforming zone.

References Cited in the file of this patent UNITED STATES PATENTS 2,407,371 Jahnig Sept. 10, 1946 2,429,721 Jahnig Oct. 28, 1947 2,560,329 Brandon July 10, 1951 2,602,771 Munday et al. July 8, 1952 

1. A METHOD OF SUPPLING HEAT TO AN ENDOTHERMIC CONTACTING ZONE EXISTING AT AN ELEVATED TEMPERATURE AND CONTAINING A MASS OF FINELY DIVIDED CONTACT MATERIAL WHICH CONTAINS COMBUSTIBLE DEPOSITS COMPRISING PASSING A PORTION OF CONTACT MATERIAL CONTAINING COMBUSTIBLE ZONE FROM THE ENDOTHERMIC ZONE TO A PRIMARY COMBUSTION ZONE WHEREIN COMBUSTIBLE DEPOSITS ARE REMOVED BY BURNING WITH AN OXYGEN CONTAINING GAS AT A TEMPERATURE ABOVE THE TEMPERATURE OF THE ENDOTHERMIC ZONE SUCH THAT THE RESULTANT CONTACT MATERIAL CONTAINS A MAJOR AMOUNT OF THE ORIGINAL COMBUSTIBLE DEPOSITS, PASSING A PORTION OF THE CONTACT MATERIAL FROM THE PRIMARY COMBUSTION ZONE TO THE ENDOTHERMIC CONTACTING ZONE, PASSING ANOTHER PORTION OF THE CONTACT MATERIAL FROM THE PRIMARY COMBUSTION ZONE TO A SECONDARY COMBUSTION ZONE WHEREIN COMBUSTIBLE DEPOSITS ARE REMOVED BY BURNING WITH OXYGEN CONTAINING GAS AT A TEMPERATURE ABOVE THE TEMPERATURE IN THE ENDOTHERMIC ZONE SUCH THAT THE RESULTANT CONTACT MATERIAL CONTAINS A MINOR AMOUNT OF THE ORGINAL COMBUSTIBLE 